This invention relates generally to refinishing or grinding machine and more particularly to devices of this type which are adapted to impart a desired, predetermined contour to portions of a workpiece, such as a turbine blade or the like.
After a period of use, the blades employed in turbine engines tend to become worn along their leading edges due to heat and abrasion from particles of sand or debris which are encountered during operation. In addition, small surface cracks can develop in the vicinity of the leading edges. When these occur, it is necessary to replace or repair the blade since such cracks will in time deepen and ultimately cause failures. Because the fabrication of these blades is expensive, involving close tolerances and special metal alloys, it has been found desirable to refinish worn or damaged blades whenever possible, instead of merely discarding them and substituting new units. Generally the blade surface is ground down at the worn area, until the cracks disappear. It has been found that removal of only minute amounts of metal, resulting in a slight undersize in the blade dimensions, refurbishes the blades so that they can again be placed in use. One of the problems encountered in removing controlled amounts of material is that it has been difficult to judge how much metal has been removed after the process has begun. In addition, achieving good uniformity from one unit to another is not had when the grinding or resurfacing is done by hand. In the latter case, it is likely that too little material will be removed on certain portions of the blade, with too much being ground off at other areas. As a rule, the leading edge on the blade is rounded along a relatively small radius, and it has been found that resurfacing such edges is exceedingly difficult to accomplish by hand, in view of the close tolerances involved.